Method of operating the electronic chronographs



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july 1.6 1946 E. GRosDQl-F METHOD OF OPERATING T11-IE ELECTRONIC CHRONOGRAPHS Fied Dec. 29, 194:5

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Patented July 16, 1946 METHOD F OPERATING THE ELECTRONIC CHRONOGRAPHS Igor E. Grosdoff, Princeton, N. J., assignor to Radio Corporation of America, a corporationof Delaware Application December 29, 1943, Serial No. 516,086

Claims.

This invention relates to switching circuits such as are suitable for controlling the operation of time measuring apparatus and the like, and has for its principal object the provision of an improved switching circuit and method of operation whereby the controlled apparatus is put into and out of operation in response to signals spaced from one another. A further object is the provision of means for automatically resetting the apparatus between both of its operations in respense to the spaced signals.

In accordance with the invention, start and stop signals are applied in common to the input circuits of start and stop channels, each oi which includes an input tube and a multivibrator connected to the output terminals of the input tube. These multivibrators are both so connected to a control tube that this tube functions to initiate the supply of the quantity to be meas ured in response to the start signal and functions to terminate this supply in response to the stop signal which is spaced from the start signal. A reset channel is connected to the same input terminal as the start and stop channels or the start signal itself may be utilized to reset the apparatus.

The start and stop channels are so interlocked that the stop channel (1) is blocked until the start signal is transmitted to the control tube and (2) is unblocked by such transmission of the start signal. The channel interlocking means utilized is a duo-diode having its anodes connected to a control element of the blocked circuit and one of its cathodes connected to the multivibrator of the start or unblocked channel. diode is connected to a delay network which is provided for precluding operation of the stop channel indefinitely or for a predetermined pe- Tied-"following the application of the start signal.

Suitablev means are provided for excluding the effect of this delay network so that the supply of the measured quantity may be terminated immediately in response to the application of a stop signal.

and immediately started by the applied signal.

The other The reset channel, in one modification.A of the invention, is so interlocked with the start The present invention is an improvement on that disclosed by a copending application Serial v Number 513,317,- iiled December 7, 1943.

The invention will be better understoodv from the following description considered in connec-v 2 tion with the accompanying drawings, and its scope is indicated by the appended claims.

Referring to the drawings:

Figure 1 is a block diagram illustrating the application of the Start stop and stop delay circuit to a device for measuring small intervals of time in terms of the cycles of a 10G-kilocycle source,

Figure 2 is a wiring diagram of the control circuit of one modication of the present invention, and

Figure 3 is a similar diagram of a second modification of the invention.

While the present invention concerns only the switching circuit of the time measuring device of Figure l, it is helpful to have a general understanding of this device as a whole. Itis essentially an electronic stop watch of high precision and is capable of measuring time intervals to one hundred thousandth of a second. Its essential parts and sequence of operation are indicated by the legends and arrow heads of Fig.1. A continuously operating -kilocyc1e quartz crystal serves as the timing element. The oscillations are passed to a mixer from which they are Areleased .by the action of the control circuit of the present invention.

A block of these oscillations representing the time interval measured is passed to the five stages of electronic counters. Here the oscillations are registered and the number is indicated by means of neon lamps. y

Each stage of the counters represents one fractional decimal place of a second. Hence the capacity of the electron part is 0.99999 of a' second in 0.00001 second steps. The whole seconds are counted and indicated on a mechanical counter with four indicating wheels. The total capacity of the counter is 999999999 seconds.

In Figure l, the circuit of Figure 2 is indicated by a box bearing the legend Start, stop and stop delay.

This circuit includes a terminal 9 and a capacitor I0 through which start and stop signals are applied to the control grids of a pair of input tubes II and I2. The tube II constitutes the input of the start channel and the tube I2 the input of the stop channel.

The output circuit of the tube II is connected to the left hand side of a multivibrator I3. This multivibrator includes two electron discharge elements I4-I5--I6 and I'I-I8|9, anode resistors 20 and 2|, and grid resistors 22-23 and 24--25. A neon tube 26 and a resistor 21 are connected in shunt to the resistor 2I for indicating when the multivibrator is in a condition to apply a positive potential to the lower control grid of a control tube 28 which is unblocked by this positive control potential to start the supply of oscillations ,to the controlled device (in the case of Fig. l, the time measuring device).

At the same time a positive potential is applied to the multivibrator grid I5, to the cathode 29 of a duo-diode 3|) through which a grid bias of the stop channel input tube I2 is controlled and to the cathode 60 of a reset channel diode 6I. The potential of the other cathode 3| of the diode 30 is derived either directly or from the 'controlled device through a lead 32 and a delay circuit constituted of multivibrators 33, 34 and 35 which are connected in cascade to produce a desired delay, for example aI two second delay. Unless .both cathodes 29 and 3| of the diode 30 are at a positive potential, the input tube I2 is biased off and a Stop signal applied to its`1ower grid is ineffective to terminate the supply of oscillations to the controlled device.

When the cathodes `29 `and 3| are both positive, however, a stop signal applied to the lower grid ot the tube I2 operates through this tube and the anode resistor 36 to apply a negative pulse to the grid of the right hand electron discharge element 4|-42-43 of a multivibrator 40. The multivibrator 4I) includes a second electron discharge element 31-38-39 and is provided with a second anode resistor 44, withgrid resistors 45-46 and 41--48 and `with a neon tube 49 and a resistor 50 connected in shunt to the resistor 44 for indicating when the multivibrator is in a condition to permit the supply of oscillations to the controlled device. It will be noted that the multivibrator control grid 42 and the upper control grid of the control tube 28 have their potential determined by the drop of the resistor 3B so that when the multivibrator element 31-38--39 is conducting, a more negative potential is applied to these grids.

.'I'he start and stop channelsare provided with test .switches 5| and 52.

A reset tube 53 and areset switch are provided for removing the negative potential from a lead B3 to establish `a standby or reset condition preparatory to operation of the circuit. In their reset condition, the `right hand sides of the multivibrators I3, 40 and 33 and the left hand sides of the `,multivibrators 34 and 35 are conducting so that anegativepotential is applied (l) to the first or lower control grid lof the control tube 2B, (2)

.to the cathode 29 of the diode 3D, (3) to the cathodes 60 and 64 of the reset channel diode 6I and (4) to the `cathode 3| of the `diode 3|! unless a switch `54 be closed for excluding the eiect of the delay network and raising the potential of the cathode 3|.

The switch 54 is closed when immediate cessation of the supply of the measured quantity in response Vto the first stop signal desired. Switches 54 and 55 are open when it is desired that the measured quantity be supplied for at least two .seconds before Yit can .be interrupted by a stop signal. -Switch 55 is closed when the measured quantity is to be supplied for an indenite time.

The reset tube 53 is controlled` from the input terminal 9 through the input tube |52 by a reset pulse which follows the stop pulse or precedes the next start ypulse so that the cycle of operation/is readily repeated without manual adjustment of the apparatus. The circuit of Fig. 2 differs from `the right to the left side of the multivibrator I3.

This transfer of current results in a more positive potential at the lower grid of the control tube 28, this tube passes current, its cathode becomesmo-re positive and. the supply of oscillations to the controlled device is started.

At the same time the cathode 29 oi the duodiode 30 and the cathode 6D of the duo-diode 6I are made more positive, so that, with the switch 54 closed, the input tube I2 is unblocked and responsive to the application of a stop signal.

'The application of a stop signal to'the tube I2 causesthis tube to draw current through the resistor 36 thereby 'transferring current from the right to the left side of the multivibrator 4|), applying a more positive potential to the cathode 64 of 5I and applying a more negative potential to the grid 42 of the multivibrator 40 and to the upper control grid of lthe control tube'28 which terminates thesupply of oscillations to the controlled device. The apparatus is now in condition to be reset by a reset pulse-applied through the terminal 9 to the input tube 62.

With switches'54 and 55 open, a negative -pulse derived from the control pulse source by way of lead 32 functions to transfer current from the left to the right side of the multivibrator 33 thereby producing a ,positive pulse which is applied through a capacitor 55 to the grid 51 of the multivibrator 34. As a result, current is transferred to the right side of this multivibrator 34. Hence grid 51 becomes positive and receptive to next negative signal from lead 32. `In a similar manner the multivibrator 35 is operated by a positive pulse from the multivibrator `34, and current is transferred tothe right side of the multivibrator 35 and the cathode 3| is made more positive. When this occurs, the multivibrator functions, as previously explained to bias oil' the control tube 28 and `interrupt the supply of `oscillations to the controlled device.

It `should be understood that the lead 32 may be connected-to any-source 'of pulses to obtain the desired delay. For example, while three-multi- `*vibrators 33, 34, 35 are `used in the circuit of Fig.

2, any other lnumber of multivibrators may be included to increase the delay,` or the pulse source may be chosen'to effect less delay.

'The circuitof Fig. Bis a two `pulse system, the

lstarting pulse being utilized to reset and immediately start the system. The system is similar in many respects to the three `pulse system of Fig. 2 Lbut differs vtherefrom in that it requires the use of less tubes. Thus the input tube II Yis utilized, together with the reset tube 53, to reset the multivibrator 4|) so that current is Atransferred toits right side. When thisloccurs, `the output tube 28 takes fcurrent, its cathode becomes more positive and the supply of .oscilla- 'tion to the controlled device is started. At the same time, the cathode 66 of a duo-diode `B'I is made Amore negative by the potential drop of the resistor 44 so thattheinput tube II is biasedioi. If the switch54 is open, the tube II is rbiased of! Aby the cathode 68 for a predetermined interval after the start signal as previously explained.

A closing pulse applied to the terminal 9 causes the tube I2 to draw current through the resistor 35. Current is thereupon transferred to the left side of the multivibrator unit 40, the cathode 66 is made more positive, the grid of the output 28 is made more positive and the supply of oscillations to the controlled device is terminated.

While the control circuit has been described as applied to a time measuring device, it should be understood that it is applicable to various types of devices having a mode of operation based on the supply of an accurately measured block of oscillations, or the like, cut from the output of a continuously operating source.

I claim as my invention:

1. The combination of a plurality of input tubes each having input and output terminals, a control tube having a control grid, a multivibrator having a rst electron discharge element connected to one of said output terminals and to said control grid and a second electron discharge element, reset means connected to the other of said output terminals and to said second electron discharge element for transferring current from one to the other of said elements, means for applying spaced signals to said input terminals, land means for blocking the second of said signals from said reset means.

2. The combination of a plurality of input tubes each having input and output terminals, a control tube having two control grids, a rst multivibrator having a first electron discharge element connected to the iirst of said output terminals and a second electron discharge element connected to one of said control grids, a second multivibrator having a iirst electron discharge element connected to the second of said output terminals and a second electron discharge element connected to the other of said control grids, reset means connected to the third of said output terminals, means for applying spaced signals to all of said input terminals, means for blocking the rst of said signals from said second multivibrator and said reset means during its transmission through the rst of said multivibrators, means responsive to said transmission for unblocking said second multivibrator to the second of said signals.

3. The combination of a plurality of input tubes each having input and output terminals, a control tube having two control grids, a rst multivibrator having a first electron discharge element connected to the first of said output terminals and a second electron discharge element connected to one of said control grids, a second multivibrator having a rst electron discharge element connected to the second of said output terminals and a second electron discharge element connected to the other of said control grids, reset means connected to the third of said output terminals, means for applying spaced signals to all of said input terminals, means for blocking the ilrst of said signals from said second multivibrator and said reset means during its transmission through the rst of said multivibrators, means responsive to said transmission for unblocking said second multivibrator to the second of said signals and means responsive to the second of said signals for unblocking said reset means to the third of said signals.

4. The combination of a pair of input tub'es each having input and output terminals, a control tube having a control grid, a multivibrator having a pair of electron discharge elements one of which is connected to one of said output ter minals and to said control grid, means including a reset element connected to said electron discharge element, means for applying spaced signals to both of said input terminals and means including a diode responsive to the current of the other of said electron discharge elements for applying a control potential whereby the rst of said signals is made ineffective to operate said multivibrator and the second of said signals is made effective to operate said multivibrator.

5. The combination of first and second input tubes provided With output terminals and with parallel-connected input circuits, means for blocking said second input tube, a control tube having two control grids, a first multivibrator having a rst electron discharge element connected to the output terminals of the first of said input tubes and a second electron discharge element, a second multivibrator having a first electron discharge element connected to the output terminals of the second of said input tubes and a second electron discharge element, means for applying spaced signals to said parallelconnected input circuits, means responsive to current produced in the second electron discharge element of said first multivibrator by the first of said signals for applying a positive potential to one of said control grids and to said blocking means, means responsive to current produced in the second electron discharge element of said second multivibrator by the second of said signals for applying a negative potential to the other of said control grids, and means responsive to the third of said signals for resetting said multivibrators.

IGOR E. GROSDOFF. 

